SVGGraph options: axis_text_callback

The datatypes used in this documentation for specifying SVGGraph options
are described below. All options can be a literal value of the data type
described, a variable containing the data type, or an expression that will
produce the data type when evaluated (and they must always be valid PHP
expressions).

array

An array(), the number and data types of its members will
depend on the option for which is it used.

boolean

A boolean TRUE or FALSE value, or any values
that convert easily such as 1, "1", 0
and "".

callback

A callable function, which can be either the name of a function or an
anonymous function itself.

colour

Any of the colour values supported by SVG inside a single or double
quoted string. These include three and six digit hex codes, RGB and
RGBA colours, and colour names. SVG uses "none" for no colour,
which generally leaves things transparent.

fill

A colour value or one of the gradients and patterns supported by
SVGGraph. See the SVGGraph colours page
for details.

integer

A negative or positive whole number or 0.

number

Any number supported by PHP, for example 1 or
-3.2 or 1.63e5 or M_PI.

string

Single or double quoted strings. Remember to double-quote your strings
if you are inserting a line break: "Line 1\nLine 2".

Per-dataset options allow specifying one option for all datasets or an
array of options to be used for each dataset in turn. If there are more
datasets than entries in the option array, the sequence will be repeated.

For this example, the widgets for all datasets will taste of banana. The
graph will use red widgets for dataset 0, green widgets for dataset 1 and blue
widgets for dataset 2. Dataset 3 repeats the sequence so its widgets will be
red, dataset 4 will have green widgets and dataset 5 will have blue
widgets.

This option allows you to specify a function for formatting the text of the
axis division labels. This should be either a string containing the name of the
function to use or an anonymous function.

The function should have this signature:

function callback($value);

The function will be passed one value corresponding to its position on the axis
and it should return the string to display. Here is an example using an
anonymous function:

$settings['axis_text_callback'] = function($v) {
return "[{$v}]";
};

This will display the labels wrapped inside square brackets.

Note: for associative arrays the value passed to the function for the X axis
labels is the numeric position of the data item and not its array key. The
callback function is actually passed a second, optional value containing the
associative array key:

function callback($array_index, $key);

For the Y-axis the callback function is called with the same value in both
arguments.

To set a callback for each axis separately, use the axis_text_callback_x and
axis_text_callback_y options.